Recovery in pupillometric non-visual functions following chiasmal decompression in pituitary adenoma

BackgroundThis study investigates visual and non-visual (i.e., pupillometric) changes associated with optic nerve compression and decompression, and the potential role of chromatic pupillometry as an objective evaluation tool for visual dysfunction in pituitary adenoma (PA). MethodsThis longitudinal study included 27 patients with PA (median age = 55.4 years [IQR=23.4]) and 41 age-matched controls (53.6 [13.7] years), evaluated pre-operatively (7.0 {+/-} 5.4 weeks prior to surgery) and post-operatively (12.0 {+/-} 1.5 weeks post-surgery) with handheld chromatic pupillometry, in addition to comprehensive neuro-ophthalmological and neuroimaging examinations. Pupillometric features were analyzed for associations with structural changes and visual outcomes. ResultsTranssphenoidal surgery significantly reduced the upward displacement and increased the thickness of the optic chiasm measured on MRI (p<0.001). Pupillary responses improved post-operatively, including increased maximum constriction to both red and blue light, but remained below control levels (p<0.05). In patients with full visual field index (VFI) recovery (n=5), pupillometric responses were comparable to controls (p>0.05) while patients without recovery exhibited persistent deficits in these metrics. Remarkably, melanopsin-driven post-illumination pupil responses (PIPR) improved significantly, reaching control values post-operatively (p>0.05), regardless of VFI recovery. Structural recovery correlated with improved VFI ({rho}= -0.62, p<0.001) and with maximum constriction to red light ({rho}= -0.47, p=0.004). ConclusionsPA surgery leads to a consistent recovery in pupillary light responses that correlate with clinical structural and functional changes observed in PA patients. Notably, melanopsin-mediated responses normalized post-operatively even in patients without VFI recovery, suggesting that non-visual pathways can recover independently of vision. What is already known on this topicPituitary adenomas frequently cause optic chiasm compression, leading to visual field loss and sleep disturbances. While transsphenoidal surgery can relieve the structural compression, functional recovery of visual and non-visual pathways remains variable and difficult to predict with existing clinical tests such as perimetry, OCT, or MRI. What this study addsIn this prospective study, handheld chromatic pupillometry objectively detected recovery in pupillary light responses after pituitary adenoma surgery, in parallel with structural and visual improvements. Notably, melanopsin-driven post-illumination pupil responses normalized even in patients without visual field recovery, suggesting that non-visual pathways may recover independently of vision. How this study might affect research, practice or policyThese findings establish handheld chromatic pupillometry as a sensitive, non-invasive biomarker to monitor both visual and non-visual functional outcomes after chiasmal decompression. Incorporating this approach into clinical and research protocols could improve postoperative monitoring and guide future work linking visual and systemic recovery in pituitary adenoma.